Plankton are small, often microscopic, creatures that largely just drift with the ocean current (as opposed to animals like fish that can swim through the current). Despite being small, they pack a big punch in marine ecosystems because a wide variety of marine life survives only by eating plankton.

Small plankton volume

Fish larvae abundance

Fish larvae diversity

Figure App.F.15.6. Mean species richness (top panels) and mean Gini-Simpson diversity (bottom panels) of fish larvae (ichthyoplankton) collected in net samples during spring CalCOFI cruises at sites in the Channel Islands National Marine Sanctuary (CINMS) region (left panels) and over the Southern California Shelf (right panels) from 1978 to 2015. Species richness is the number of species present in a net sample. Gini-Simpson diversity (1-λ form) takes into account the number of species present, as well as the relative abundance of each species. Species richness tends to increase in El Niño years due to influx of central Pacific species to the shelf. Gini-Simpson diversity is high when individuals are well-distributed among species suggesting that the 2015 spike in richness was not due to rare species. Sampling sites are shown on Figure App.F.12.17. Symbols on the graph are explained in the caption for Figure App.F.12.18. Data source: CalCOFI; Figure: A. Thompson/NOAA

Figure App.F.15.6. Mean species richness (top panels) and mean Gini-Simpson diversity (bottom panels) of fish larvae (ichthyoplankton) collected in net samples during spring CalCOFI cruises at sites in the Channel Islands National Marine Sanctuary (CINMS) region (left panels) and over the Southern California Shelf (right panels) from 1978 to 2015. Species richness is the number of species present in a net sample. Gini-Simpson diversity (1-λ form) takes into account the number of species present, as well as the relative abundance of each species. Species richness tends to increase in El Niño years due to influx of central Pacific species to the shelf. Gini-Simpson diversity is high when individuals are well-distributed among species suggesting that the 2015 spike in richness was not due to rare species. Sampling sites are shown on Figure App.F.12.17. Symbols on the graph are explained in the caption for Figure App.F.12.18. Data source: CalCOFI; Figure: A. Thompson/NOAA